Optimizing cycling skinsuit design through an integrated wind-tunnel and CFD workflow

This paper explores the use of computational fluid dynamics (CFD) in the design of cycling skinsuits with varying surface roughness. Traditional skinsuit design involves a complex and time-consuming process by wind tunnel experiments. CFD could potentially offer an alternative for predicting the performance and designing rider-specific skinsuits, though accurately modelling fabric surface roughness is challenging. The study characterizes skinsuit fabrics based on an equivalent sand-grain roughness height (k_S) value derived from drag reduction measurements on cylinders covered with specific fabrics. Three skinsuits, created from these fabrics, are assessed on a full-scale cyclist mannequin. For two of the three suits, the calculated drag area is within 0.6 % of the wind tunnel (WT) results. In the case of the third suit, the deviation with the WT drag area is 1.6 %. The CFD simulations reveal valuable insights, such as the impact of including variable k_S values on the location of flow separation, the local distribution of skin friction and pressure drag, and their effects on the near flow field. The agreement between WT and CFD results suggests the potential of CFD for designing aerodynamically optimized skinsuits for individual riders, while further research is recommended to refine and validate this approach.